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598971bfbd
cfq caches the associated cfqq's for a given cic. The cache needs to
be flushed if the cic's ioprio or blkcg has changed. It is currently
done by requiring the changing action to set the respective
ICQ_*_CHANGED bit in the icq and testing it from cfq_set_request(),
which involves iterating through all the affected icqs.
All cfq wants to know is whether ioprio and/or blkcg have changed
since the last flush and can be easily achieved by just remembering
the current ioprio and blkcg ID in cic.
This patch adds cic->{ioprio|blkcg_id}, updates all ioprio users to
use the remembered value instead, and updates cfq_set_request() path
such that, instead of using icq_get_changed(), the current values are
compared against the remembered ones and trigger appropriate flush
action if not. Condition tests are moved inside both _changed
functions which are now named check_ioprio_changed() and
check_blkcg_changed().
ioprio.h::task_ioprio*() can't be used anymore and replaced with
open-coded IOPRIO_CLASS_NONE case in cfq_async_queue_prio().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
79 lines
2 KiB
C
79 lines
2 KiB
C
#ifndef IOPRIO_H
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#define IOPRIO_H
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#include <linux/sched.h>
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#include <linux/iocontext.h>
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/*
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* Gives us 8 prio classes with 13-bits of data for each class
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*/
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#define IOPRIO_BITS (16)
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#define IOPRIO_CLASS_SHIFT (13)
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#define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
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#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
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#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
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#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
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#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
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/*
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* These are the io priority groups as implemented by CFQ. RT is the realtime
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* class, it always gets premium service. BE is the best-effort scheduling
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* class, the default for any process. IDLE is the idle scheduling class, it
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* is only served when no one else is using the disk.
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*/
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enum {
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IOPRIO_CLASS_NONE,
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IOPRIO_CLASS_RT,
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IOPRIO_CLASS_BE,
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IOPRIO_CLASS_IDLE,
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};
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/*
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* 8 best effort priority levels are supported
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*/
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#define IOPRIO_BE_NR (8)
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enum {
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IOPRIO_WHO_PROCESS = 1,
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IOPRIO_WHO_PGRP,
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IOPRIO_WHO_USER,
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};
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/*
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* Fallback BE priority
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*/
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#define IOPRIO_NORM (4)
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/*
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* if process has set io priority explicitly, use that. if not, convert
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* the cpu scheduler nice value to an io priority
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*/
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static inline int task_nice_ioprio(struct task_struct *task)
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{
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return (task_nice(task) + 20) / 5;
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}
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/*
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* This is for the case where the task hasn't asked for a specific IO class.
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* Check for idle and rt task process, and return appropriate IO class.
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*/
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static inline int task_nice_ioclass(struct task_struct *task)
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{
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if (task->policy == SCHED_IDLE)
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return IOPRIO_CLASS_IDLE;
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else if (task->policy == SCHED_FIFO || task->policy == SCHED_RR)
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return IOPRIO_CLASS_RT;
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else
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return IOPRIO_CLASS_BE;
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}
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/*
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* For inheritance, return the highest of the two given priorities
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*/
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extern int ioprio_best(unsigned short aprio, unsigned short bprio);
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extern int set_task_ioprio(struct task_struct *task, int ioprio);
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#endif
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